Fipronil sulfone (FS) is known to adversely affect the organs and organ systems of all living organisms exposed to this substance. The present study was performed to examine the effects of FS on the fertilizing capacity of boar spermatozoa. The boar sperm samples were subjected to varying concentrations of FS (10 - 200 µM) for two different incubation times (30 min and 2 hrs). Sperm motility, viability, acrosome integrity, and production of intracellular reactive oxygen species (ROS) were then evaluated. Real-time PCR was conducted to analyze the RNA expression of ODF2, ZPBP2, HSPA8, and AKAP4, which are associated with the integrity of the sperm fibrous sheath and sperm movement. A dose-dependent motility reduction was observed in sperm exposed to FS during both incubation periods compared to the controls. Higher percentages of viable sperm were observed in the controls, while viability was significantly decreased in sperm incubated with 20 - 200 µM FS. Acrosomes were damaged in sperm incubated with 200 µM FS after 30 min of incubation. Higher levels of intracellular reactive oxygen species (ROS) were produced in sperm exposed to FS after 2 hrs of incubation. Also, the mRNA expression levels of ODF2, ZPBP2, and AKAP4, which are associated with fertilizing capacity, were downregulated in sperm exposed to FS compared to the controls. Direct exposure to metabolites of specific pesticides such as fipronil affects male fertility due to their effects on sperm characteristics. It is thus necessary to screen metabolites that cause reproductive physiotoxicity to protect health and prevent sub-/infertility in animals.
Figures & Tables
Fig. 1. Fluorescence microscopic images of sperm viability (A) and acrosomal integrity (B). A green color circle represents live spermatozoa, while a red color circle represents dead sperm (A). Sperm heads displaying green fluorescence were considered to have an intact acrosome, while partial green fluorescence or its absence in the head was indicative of spermatozoa with damaged acrosome with loss of acrosome integrity (B).